Aha! I always thought they WERE crows. Hmmmm, wonder if these are the same birds that come out every spring and completely cover your lawn.....looking for who know's what? Quite possibly. Either grackles, or maybe starlings -- both tend to show up in groups and check out lawns.
Starling:
The starlings tend to be more methodical about their yard searches. Starlings are not a native North American bird, by the way. Several decades ago some were on display in Central Park in New York City (part of a "birds mentioned in Shakespeare" exhibit), and the starlings got loose. They were so successful in the wild that they're now one of the most common birds in North America, displacing a lot of native birds, and are a real pest in some areas. And they can travel in huge flocks:
Like pigeons, they're sometimes denounced as "rats with wings", but they have a few saving graces -- they're rather cute, and they make amusing noises. If kept as a pet, they can even learn to talk pretty well, like a mockingbird or parrot.
Here's a starling story from my family. Several decades ago, my grandfather, WW1 USMC sergeant and well known Superior Court Judge, once had a zillion starlings fly into the tree outside his study. They made such a racket that he went outside to try and shoo them away. That didn't work so he tossed a couple of cherry bombs up into the tree. That didn't work either, so he got his shotgun and blew off a couple of shells. That did work.
As he sat at the kitchen table, cleaning his scattergun, a town cop opened the back door and strolled in. "Your honor..." he started to say and stopped when Poppop snapped the gun closed and pointed it at him.
"Go back outside and knock" he said. The poor cop carefully made his way back outside and knocked. "Come in!" said my grandfather, as he cheerfully went back to cleaning. "Uhh, sir, the neighbors called and asked if you could not shoot your shotgun off in the neighborhood?". "Oh. Sure" said Poppop. Ahh, the thirties.